Status and reaction to anoxia of rat fetuses developing in conditions of placental insufficiency

Significant adverse correlation of the fetus mass and the degree of its hydration was noted at term in rats with placental insufficiency induced by ligation of about 40% of preplacental vessels on the 16th day of gestation. Disorders revealed in transplacental water-salt metabolism are apparently of some importance for the pathogenesis of fetal growth retardation. Even moderate retardation alters fetal respiratory activity in anoxia, which is associated with the changes in the function of respiratory centres and neuromuscular abnormalities.     

In vitro attachment of bilins to apophycocyanin. III. Properties of the phycoerythrobilin adduct

Addition of phycoerythrobilin (PEB) to apophycocyanin at pH 7.0 resulted in covalent adduct formation. The adduct showed absorbance maxima at 575 and 605 nm and fluorescence emission maxima at 582 and 619 nm. Analysis of bilin peptides obtained upon tryptic digestion of the adduct showed residues alpha-Cys-84 and beta-Cys-82 to be the sites of bilin addition. The product of PEB addition at the alpha-Cys-84 site was shown by 1H NMR analysis to be a dihydrobiliviolinoid peptide-linked pigment differing in structure from that of the naturally occurring PEB-adduct by the presence of a double bond in between C2 and C3 of ring A. At the beta-Cys-82 site both a dihydrobiliviolinoid and a PEB adduct were obtained. Biliverdin also formed a covalent adduct with apophycocyanin with a lambda max of 669 nm. These results show that the spontaneous in vitro addition of bilins to apophycocyanin does not exhibit the site selectivity of bilin addition observed in vivo. This offers the opportunity to form novel semisynthetic phycobiliproteins.     

Mutability of the LYS2 gene in diploid saccharomycete yeasts. I. The occurrence of spontaneous mutants and mutants induced by x-ray and ultraviolet radiation

More than 3000 spontaneous and induced lys2 mutants were obtained in haploid and diploid strains of yeast Saccharomyces. The ability to utilize alpha-aminoadipate was used for lys2 mutant screening. The spontaneous and induced mutation rates were measured in haploid and diploid strains. Mitotic segregation of pho1 marker linked to LYS2 was studied in lys2 mutants obtained in diploid strains. Fertility of diploid lys2 mutants was tested. The conclusion to be drawn from the data presented is that mutations appeared in one of two homologous chromosomes and then segregated by mitotic homozygotization.     

Construction of a cDNA for the human c-fes protooncogene protein-tyrosine kinase and its expression in a baculovirus system.

Previous studies have established that the 93-kDa protein-tyrosine kinase (PTK) encoded by the human c-fes protooncogene plays an active role in the induction of terminal myeloid differentiation. However, this enzyme is expressed at very low levels in myeloid cells, making isolation of sufficient quantities for detailed biochemical analysis difficult. To overcome this problem, we used the polymerase chain reaction to construct a full-length c-fes cDNA from overlapping 5' and 3' partial cDNA sequences. The c-fes cDNA was expressed at high levels in a baculovirus system, and the catalytically active recombinant c-fes gene product p93c-fes was partially purified by DEAE-Sepharose and tyrosine-agarose chromatography. Recombinant p93c-fes was indistinguishable from the native protein in terms of its apparent molecular weight following SDS-PAGE, catalytic activity, Km for poly(Glu,Tyr)4:1, antigenicity, and phosphopeptide pattern generated with Staphylococcus aureus protease.     

Genes of the R-phycocyanin II locus of marine Synechococcus spp., and comparison of protein-chromophore interactions in phycocyanins differing in bilin composition

R-phycocyanin II (RPCII) is a recently discovered member of the phycocyanin family of photosynthetic light-harvesting proteins. Genes encoding the and subunits of RPCII were cloned and sequenced from marine Synechococcus sp. strains WH8020 and WH8103. The deduced amino acid sequences of RPCII were compared to two other types of phycocyanin, C-phycocyanin (CPC) and phycoerythrocyanin (PEC). These three types vary in the composition of their covalently bound bilin prosthetic groups. In terms of amino acid sequence identity RPCII is highly homologous to CPC and PEC, suggesting that the known three-dimensional structures of the latter two are representative of RPCII. Thus the amino acid residues contacting the three bilins of RPCII could be inferred and compared to those in CPC and PEC. Certain residues were identified among the three phycocyanins as possibly correlating with specific bilin isomers. In overall sequence RPCII and CPC are more homologous to one another than either is to PEC. This probably reflects functional homology in the roles of RPCII and CPC in the transfer of light energy to the core of the phycobilisome, a function not attributed to PEC. The genomes of Synechococcus sp. strains WH8020, WH8103 and WH7803 share homologous open reading frames in the vicinity of RPCII genes. The nucleotide sequence extending 3 from RPCII genes in strain WH8020 revealed two open reading frames homologous to components of an CPC phycocyanobilin lyase. These open reading frames may encode a lyase specific for the attachment of phycoerythrobilin to RPCII.     

Cryptomonad biliproteins — an evolutionary perspective

Each cryptomonad strain contains only a single spectroscopic type of biliprotein. These biliproteins are isolated as 50000 kDa '₂ complexes which carry one bilin on the and three on the subunit. Six different bilins are present on the cryptomonad biliproteins, two of which (phycocyanobilin and phycoerythrobilin) also occur in cyanobacterial and rhodophytan biliproteins, while four are known only in the cryptomonads. The subunit is encoded on the chloroplast genome, whereas the subunits are encoded by a small nuclear multigene family. The subunits of all cryptomonad biliproteins, regardless of spectroscopic type, have highly conserved amino acid sequences, which show > 80% identity with those of rhodophytan phycoerythrin subunits. In contrast, cyanobacteria and red algal chloroplasts each contain several spectroscopically distinct biliproteins organized into macromolecular complexes (phycobilisomes). The data on biliproteins, as well as several other lines of evidence, indicate that the cryptomonad biliprotein antenna system is primitive and antedates that of the cyanobacteria. It is proposed that the gene encoding the cryptomonad biliprotein subunit is the ancestral gene of the gene family encoding cyanobacterial and rhodophytan biliprotein and subunits.Abbreviations Chl chlorophyll - CER chloroplast endoplasmic reticulum - SSU rRNA small subunit ribosomal RNA     

AN UNUSUAL PHYCOCYANOBILIN-CONTAINING PHYCOERYTHRIN OF SEVERAL BLUISH-COLORED,ACROCHAETIOID, FRESHWATER RED ALGAL SPECIES1

The reproductive biology and phycobiliproteins of four different culture isolates of the freshwater algae Audouinella and‘Chantransia’were investigated.‘Chantransia’sp. (3585/UTEX 2623) and Audouinella macrospora (Wood) Sheath et Burkholder (3394,3395) from California and Minnesota reproduced only by monospores. However, A. macrospora (3603/Necchi 1) reproduced by monosporangia that formed successive generations of the Audouinella phase, and Batrachospermum shoots developed from the basal and erect systems. The major light-harvesting phycobiliprotein in all of these isolates was a phycocyanobilin-containing phycoerythrin not previously detected in red algae or cyanobacteria. As in the commonly found R- and B-phycoerythrins, Audouinella phycoerythrin had a native molecular mass of ～ 240,000 and was made up of α, β, and γ subunits. Audouinella phycoerythrin carried two phycoerythrobilins on the α subunit; one phycourobilin, one phycoerythrobilin, and one phycocyanobilin on the β subunit; and one phycourobilin and two phycoerythrobilins on the γ subunit. With excitation at 495, 563, or 603 nm, the fluorescence emission peak of Audouinella phycoerythrin was at 626 nm, showing that phycocyanobilin was the terminal energy acceptor.     

Bimodal effect of phorbol ester on B cell activation. Implication for the role of protein kinase C.

The role of protein kinase C PKC in B cell activation is controversial. These studies were undertaken to determine whether protein kinase C has a stimulatory or inhibitory role in B cell activation. We found that treatment of B cells for a short period of time (30 min) with the PKC activator phorbol 12,13-dibutyrate (PDBU) primed the cells for enhanced proliferative responses to anti-immunoglobulin (anti-Ig) antibody whereas treatment for a longer period of time (3 h or more) resulted in suppression of proliferation. The enhanced proliferative response to treatment of B cells with PDBU for short periods of time was associated with inhibition of anti-Ig-stimulated increases in phosphatidyl 4,5-bisphosphate (PIP2) hydrolysis and inhibition of increases in [Ca2+]i, indicating that activation of PKC per se might be sufficient for enhancing B cell activation. The time-dependent effect of phorbol esters on the inhibition of B cell proliferation was found to be closely correlated with the kinetics of disappearance of PKC as measured by Western blot and by enzymatic activity but not with inhibition of [Ca2+]i and PIP2. These data demonstrate a bimodal time-dependent effect of PDBU on B cell activation and suggest that (a) the inhibitory effect of phorbol ester on anti-Ig-induced proliferation may be due to the disappearance of PKC rather than to the inhibition of PIP2 and Ca2+; and (b) the early activation of PKC is a stimulatory rather than an inhibitory signal in the induction of B lymphocyte proliferation by anti-Ig.